This invention is directed to a device for the manipulation and heating of components on circuit boards for soldering and desoldering these components to the circuit board.
It has been previously proposed, and devices have been built, based upon the principle of utilizing a hot gas to assist in the soldering and desoldering of components to printed circuit boards and the like. The simplest of these devices consists of simply a hot air gun which is capable of being hand held and discharging a stream of heated air out of an appropriate nozzle. While this certainly has its utilitarian merits, and is very useful for minor repairs and the like on printed circuit boards, it does not lend itself to large scale manufacturing or repair of printed circuit boards.
In essence, the hand held guns can take one of two forms. First, they could have a very small discharge orifice for the hot air, allowing for pin point use of the gun at a very small area, or secondly, they could have a very large discharge orifice, allowing for discharge of heated air over a substantially greater area. Because of the compactness of printed circuit boards and the like, the guns having a large discharge orifice are not very useful. On a printed circuit board, a first connection may be located very closely to a second connection. If a gun with a large orifice is utilized, the possibility exists of melting more solder connections than is desirable. As such, in attempting to remove a component at a first solder connection inadvertently the solder at the second solder connection can also be softened and caused to flow leading to loss of the component or shorting of the board caused by the solder flow.
The hand held guns which have a small discharge orifice, while providing the control necessary to work on a printed circuit board, unfortunately are not useful in desoldering IC's (integrated circuits) mounted on a printed circuit board because of the multiple connectors which must be simultaneously desoldered in order to remove the IC.
A further device is known which is directed to solely removing IC's which have pins which pass through holes on printed circuit boards. This device utilizes a pool of molten solder into which the portions of the pins of the IC's which extend below the bottom of the printed circuit board are dipped. Heat from the molten solder is transferred to the pins to melt the solder connections between the pins and the board. The IC is then lifted from the board by a spring loaded gripper. While this device certainly has utilitarian function to remove IC's of the type having pins which pass through holes in a printed circuit board, it is useless with respect to soldering those same IC's on to a board or in any way whatsoever with regard to IC's which only attach to the top surface of a printed circuit board.
A further device for removing IC's which are simply attached to the top surface of a printed circuit board utilizes a vacuum head having a plate with a plurality of holes arranged in a grid on the plate. The vacuum plate is then encircled with a heating device such that the vacuum head and an IC located in the vacuum head are heated to a temperature sufficient to melt the solder attaching the IC to the circuit board. Since this device utilizes heat conducted by the IC itself to desolder the IC, it of course is useful for desoldering the IC's wherein the IC is being removed because of a malfunction or the like. The device, however, would not be useful for soldering IC's to the board for the very reason that the IC's must be heated to serve as heat conductors for the soldering operation. This would be very detrimental to heat sensitive IC's and the like.
A final device utilizes a blower and heater to pass hot air through both an upper and lower hot air tube. A printed circuit board is positioned between the discharge orifices of both the upper and lower hot air tubes with the hot air then serving to melt the solder for a desoldering operation. Since the pins of the IC are located on both sides of the body of the IC, the IC itself is also placed into the hot air stream, such that it is in the hot environment of the hot air. This could lead to compromising of the function of the IC if attempts were made to use this device for a soldering operation. Further with this device, since the hot air discharge tubes are of a diameter sufficiently greater than most IC'S, the heat not only is directed to the IC which is currently being desoldered, but it is also spread to adjacent IC's, with the potential of desoldering these adjacent IC's or damaging them because of exposure to heat.